Electric drive module

ABSTRACT

An electric drive unit having a stator, a rotor received in the stator and rotatable about a central longitudinal axis, and an inverter assembly that includes a plurality of power semiconductors, a plurality of heat sinks and an end plate. The power semiconductors are thermally coupled to the heat sinks. Each of the heat sinks has a plurality of fins that extend into a flow channel that is coaxial with the plurality of sets of field windings. The end plate is coupled to the power semiconductors and has a projection, which is sealingly coupled to the stator and which and partly defines an annular cavity, and a coolant port that is coupled in fluid communication with the annular cavity. The flow channel is in fluid communication with and disposed in a flow path between the annular cavity and the cooling channels in the stator body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/691,244 filed Mar. 10, 2022, which is a continuation of U.S. patentapplication Ser. No. 17/501,189 filed Oct. 14, 2021 (now U.S. patentSer. No. 11/303,183 issued Apr. 12, 2022), which is a bypasscontinuation of International Patent Application No. PCT/US2020/029925filed Apr. 24, 2020, which claims the benefit of U.S. ProvisionalApplication No. 62/838,893 filed Apr. 25, 2019 and U.S. ProvisionalApplication No. 62/904,199 filed Sep. 23, 2019. The disclosures of eachof the above-referenced applications is incorporated by reference asfully set forth in detail herein.

FIELD

The present disclosure relates to an electric drive module.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

While there is increasing interest in the electrification of vehicledrivelines, there are significant issues that must be overcome beforevehicles with electrified drivelines substantially displace vehicledrivelines that are powered solely by internal combustion engines. Someof these issues include the cost of the electrified driveline, thevolume of the electrified driveline and its ability to be packaged intoavailable space within a vehicle, as well as the robustness of theelectronics that are employed to operate and control the electrifieddriveline.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

In one form, the present disclosure provides an electric drive modulethat includes a housing assembly, an electric motor, and an inverter.The electric motor is received in the housing assembly and has a statorand a rotor. The stator has a plurality of sets of field windings and aplurality of phase leads. A plurality of stator cooling passages areformed through the stator. Each of the sets of field windings isdisposed about a rotary axis. Each of the phase leads is electricallycoupled to a corresponding one of the sets of field windings. The rotoris disposed in the stator for rotation about the rotary axis. Theinverter has a retaining member, an end plate, a circuit board assembly,a plurality of power semiconductor devices, and one or more heat sinks.The retaining member is received between the housing assembly and anaxial end of each of the sets of field windings. The end plate isfixedly and sealingly coupled to the retaining member. At least aportion of the circuit board assembly has an annular shape that isdisposed about the rotor and is received in the retaining member on afirst side of the end plate. The circuit board assembly is electricallycoupled to the phase leads. Each of the power semiconductor devices hasa plurality of pin terminals and a power terminal that is electricallycoupled to one of the pin terminals. The power semiconductor devices arearranged in an annular manner within the retaining member such that thepower terminals are disposed on a second side of the end plate that isopposite the first side. The pin terminals of the power semiconductordevices extend through the end plate and are electrically coupled to thecircuit board assembly. The power terminal of each of the powersemiconductor devices is mounted to the one or more heat sinks. Each ofthe one or more heat sinks has a plurality of fins. The fins of the heatsinks are disposed in an annular region that is adjacent to the axialends of the sets of field windings. The annular region is in fluidcommunication with the stator cooling passages. An inlet port is formedthrough the end plate. The inlet port is adapted to receive a liquidcooling fluid therethrough. The inlet port is coupled in fluidcommunication to the annular region.

In another form, the present disclosure provides an electric drivemodule that includes a housing assembly, an electric motor and aninverter. The electric motor is received in the housing assembly and hasa stator and a rotor that is rotatable relative to the stator about arotary axis. The stator has a plurality of sets of field windings and aplurality of phase leads. Each of the phase leads is electricallycoupled to a corresponding one of the sets of field windings. Theinverter has a retaining member, an end plate, a circuit board assembly,a plurality of power semiconductor devices, and one or more heat sinks.The retaining member is received between the housing assembly and anaxial end of each of the sets of field windings. The end plate isfixedly and sealingly coupled to the retaining member. The circuit boardassembly is received in the retaining member on a first side of the endplate. Each of the power semiconductor devices has a plurality of deviceterminals and a power terminal that is electrically coupled to one ofthe device terminals. The power semiconductor devices are arrangedwithin the retaining member such that the power terminals are disposedon a second side of the end plate that is opposite the first side. Thedevice terminals of the power semiconductor devices extend through theend plate and are electrically coupled to the circuit board assembly.The power terminal of each of the power semiconductor devices is mountedto the one or more heat sinks. Each of the one or more heat sinks has aplurality of fins. The fins of the heat sinks are disposed in a regionthat is adjacent to the axial ends of the sets of field windings. Aninlet port is formed through the end plate and is configured to receivea liquid cooling fluid therethrough. The inlet port being coupled influid communication to the region.

In still another form, the present disclosure provides an electric driveunit that includes a stator, a rotor, and an inverter assembly. Thestator has a stator body and a plurality of sets of field windings. Thestator body defines a plurality of cooling channels that extendlongitudinally through the stator body. Each of the sets of fieldwindings is fixedly coupled to the stator body and is circumferentiallyspaced apart about a central longitudinal axis. The rotor is received inthe stator and is rotatable about the central longitudinal axis. Theinverter assembly includes a plurality of power semiconductors, aplurality of heat sinks and an end plate. Each of the powersemiconductors is thermally coupled to a corresponding one of the heatsinks. Each of the heat sinks has a plurality of fins that extend into aflow channel that is coaxial with the plurality of sets of fieldwindings. The end plate is coupled to the power semiconductors and has aprojection and a coolant port. The projection is sealingly coupled tothe plurality of sets of field windings and partly defines an annularcavity. The coolant port is coupled in fluid communication with theannular cavity. The flow channel is in fluid communication with anddisposed in a flow path between the annular cavity and the coolingchannels in the stator body.

In a further form, the present disclosure provides an electric driveunit that includes a motor assembly having an electric motor and aninverter assembly. The electric motor has a plurality of sets of fieldwindings and defines a plurality of cooling channels. Each of the setsof field windings includes a phase terminal. The inverter assembly has aretainer, a plurality of power semiconductors, a circuit board, firstand second bus bars, a plurality of conductor plates, and a plurality ofheat sinks. The retainer includes an annular end plate that is sealinglycoupled to the electric motor. Each of the power semiconductors has aplurality of device terminals that are received through the annular endplate. Each of the power semiconductors is electrically coupled to thefirst and second bus bars. Each of the conductor plates is electricallycoupled to a corresponding set of the power semiconductors and acorresponding one of the phase terminals. The heat sinks aremechanically and thermally coupled to the power semiconductors. Thepower semiconductors and the heat sinks are disposed concentric with theplurality of sets of field windings. The end plate defines a coolanttube. The end plate and the electric motor cooperate to form an annularcavity that is in fluid communication with the coolant tube. The heatsinks have fins that are disposed in a flow channel. The flow channel isdisposed in fluid communication between the annular cavity and thecooling channels.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIGS. 1 and 2 are longitudinal section views of an exemplary electricdrive module constructed in accordance with the teachings of the presentdisclosure;

FIGS. 3 and 4 are sections view of a portion of the electric drive unitof FIG. 1, illustrating the construction of a motor assembly in moredetail;

FIGS. 5 and 6 are partly sectioned views of the electric drive unit ofFIG. 1;

FIGS. 7 and 9 are perspective views of a portion of the motor assembly,illustrating a portion of an inverter in more detail;

FIGS. 8 and 10 are similar to FIGS. 7 and 9, respectively, but depict aportion of the inverter in a see-through manner so that a plurality ofMOSFET's are more easily seen;

FIG. 11 is a perspective view of a portion of the inverter, illustratinga MOSFET as connected to a heat sink;

FIG. 12 is a rear perspective view illustrating a MOSFET as connected toa heat sink;

FIG. 13 is a rear perspective view of a heat sink;

FIG. 14 is an exploded perspective view of a MOSFET, a solder materialand a heat sink;

FIG. 15 is a perspective view of the inverter shown with an end plate;

FIG. 16 is a sectional view of a portion of the electric drive unit ofFIG. 1, illustrating a sensor assembly having a TMR sensor that ismounted to a control board and a magnet that is coupled for rotationwith a rotor of the motor assembly;

FIG. 17 is a perspective view of the electric drive unit of FIG. 1;

FIG. 18 is a rear perspective view of a portion of a housing of theelectric drive unit of FIG. 1;

FIG. 19 is a perspective view of a portion of the electric drive unit ofFIG. 1 with the portion of the housing shown in FIG. 18 removed;

FIG. 20 is similar to that of FIG. 19, but depicting the electric driveunit with a portion of a transmission and a differential assemblyremoved;

FIG. 21 is similar to that of FIG. 20, but depicting a further portionof the housing removed to better show a portion of the transmission;

FIG. 22 is a sectional view of a portion of the electric drive unit thatis shown in FIG. 21;

FIGS. 23 through 44 are section views of various portions of theelectric drive unit of FIG. 1, depicting the flow of cooling andlubricating oil through various portions of the electric drive unit;

FIG. 45 through 60 are various views of an alternately configuredinverter;

FIG. 61 is a perspective view depicting the mounting of a cover to theinverter of FIG. 45 and the assembly of the inverter to a housing of analternately configured electric drive unit;

FIG. 62 is similar to the view of FIG. 61 with the cover removed fromthe inverter;

FIG. 63 is similar to the view of FIG. 62 with a bearing supportremoved;

FIG. 64 is similar to the view of FIG. 63 with the inverter removed toshow the stator;

FIG. 65 is a section view through the alternately configured electricdrive unit depicting the flow of cooling oil through a field capacitorand to the stator;

FIG. 66 is an enlarged portion of FIG. 65;

FIG. 67 is a section view of a portion of the alternately configuredelectric drive unit depicting where cooling oil leaves a cavity thatholds a field capacitor and merges with a flow of cooling oil thatpasses through the heat sinks prior to the merged flow entering coolantpassages formed in the stator;

FIG. 68 is a front perspective view of the field capacitor;

FIG. 69 is a rear perspective view of a portion of the field capacitor;

FIG. 70 is a perspective view of a portion of the housing of thealternately configured electric drive unit showing a field capacitorcavity for holding the field capacitor;

FIG. 71 is a perspective view of a portion of the alternately configuredelectric drive unit illustrating the mounting of the field capacitor tothe housing via a plurality of screws; and

FIG. 72 is a section view of a portion of the alternately configuredelectric drive unit taken through the bearing support and illustratingan insulator axially between the circuit board assembly and a flangeformed on the bearing support.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2, an exemplary electric drive moduleconstructed in accordance with the teachings of the present disclosureis generally indicated by reference numeral 10. The electric drivemodule 10 includes a housing assembly 12, an electric motor 14, acontrol unit 16, a transmission 18, a differential assembly 20, a pairof output shafts 22 a and 22 b, a pump 24, a heat exchanger 26 (FIG. 5)and a filter 28.

The housing assembly 12 can house the electric motor 14, the controlunit 16, the transmission and the differential assembly 20. The electricmotor 14 can be any type of electric motor and can have a stator 32 anda rotor 34. The stator 32 can include field windings 36, whereas therotor 34 can include a rotor shaft 38 that can be disposed within thestator 32 for rotation about a first rotational axis 40.

The transmission 18 can include a planetary reduction 42, a shaft 44 anda transmission output gear 46. The planetary reduction can have a sungear, which can be unitarily and integrally formed with the rotor shaft38 to keep pitch line velocity as low as possible, a ring gear, whichcan be grounded to or non-rotatably coupled to the housing assembly 12,a planet carrier and a plurality of planet gears that can be journallysupported by the planet carrier and which can be meshingly engaged withboth the sun gear and the ring gear. The sun gear, the ring gear and theplanet gears can be helical gears. The shaft 44 can be mounted to a setof bearings 60 that support the shaft for rotation about the firstrotational axis 40 relative to the housing assembly 12. The transmissionoutput gear 46 can be coupled to (e.g., unitarily and integrally formedwith) the shaft 44 for rotation therewith about the first rotationalaxis 40.

The differential assembly 20 can include a final drive or differentialinput gear 70 and a differential. The differential input gear 70 can berotatable about a second rotational axis 80 and can be meshingly engagedto the transmission output gear 46. In the example provided, thetransmission output gear 46 and the differential input gear 70 arehelical gears. The differential can be any type of differentialmechanism that can provide rotary power to the output shafts 22 a and 22b while permitting (at least in one mode of operation) speeddifferentiation between the output shafts 22 a and 22 b. In the exampleprovided, the differential includes a differential case, which iscoupled to the differential input gear 70 for rotation therewith, and adifferential gearset having a plurality of differential pinions, whichare coupled to the differential case and rotatable (relative to thedifferential case) about one or more pinion axes that are perpendicularto the second rotational axis 80, and a pair of side gears that aremeshingly engaged with the differential pinions and rotatable about thesecond rotational axis 80. Each of the output shafts 22 a and 22 b canbe coupled to an associated one of the side gears for rotationtherewith. In the example provided, the output shaft 22 b is formed astwo distinct components: a stub shaft 90 and half-shaft 92. The stubshaft 90 is drivingly coupled to an associated one of the side gears andextends between an associated gear and the half-shaft 92 and issupported by a bearing 94 in the housing assembly 12 for rotation aboutthe second rotational axis 80. Each of the output shaft 22 a and thehalf-shaft 92 has a constant velocity joint 100 with a splined malestem. The splined male stem of the constant velocity joint on the outputshaft 22 a is received into and non-rotatably coupled to an associatedone of the side gears. The splined male stem of the constant velocityjoint on the half-shaft 92 is received into and non-rotatably coupled tothe stub shaft 90.

In FIGS. 3 through 6, the control unit 16 includes a power terminal 200,one or more field capacitor 202, an inverter 204 and a controller 206.The power terminal 200 can be mounted to the housing assembly 12 and canhave contacts or terminals (not shown) that can be fixedly coupled to arespective power lead 210 to electrically couple the power lead 210 tothe control unit 16. It will be appreciated that the electric motor 14can be powered by multi-phase electric AC power and as such, the powerterminal 200 can have multiple contacts or terminals to permit theseveral power leads 210 to be coupled to the control unit 16.

Each field capacitor 202 electrically couples an associated one of thepower leads 210 to the inverter 204. In the example provided, each fieldcapacitor 202 is relatively small and is disposed in an annular spacebetween the inverter 204 and the housing assembly 12. The annular spacecan be disposed adjacent to an end of a body of the stator 32 from whichthe field windings 36 extend. Each field capacitor 202 can be mounted tothe inverter 204.

With reference to FIGS. 3, 4 and 7 through 10, the inverter 204 can bean annular structure that can be mounted about the field windings 36that extend from the body of the stator 32. In the example provided theinverter 204 includes a transistor assembly 250 and a circuit boardassembly 252. The transistor assembly 250 can comprise a plurality ofsurface mount MOSFET's 260, a plurality of heat sinks 262, and aretaining member 264.

With reference to FIGS. 11 through 14, each of the MOSFET's 260 caninclude a plurality of device or pin terminals 270 a, 270 b and 270 cand a surface-mount power terminal (not specifically shown). Thesurface-mount power terminal of each MOSFET 260 can be soldered to anassociated one of the heat sinks 262. In the example provided, each heatsink 262 has a base 280 and a plurality of fins 282 that extend from thebase 280. The base 280 can optionally define a pocket 288 that isconfigured to receive the MOSFET 260. The pocket 288 has a bottomsurface 288 a. A riser 288 b, which is a tapered surface of the pocketthat provides clearance between the heat sink 262 and the MOSFET 260,can be provided to permit air to vent from/prevent air entrapment in thepocket 288 when the MOSFET 260 is received into the pocket 288 andsoldered to the bottom surface 288 a. The solder can be placed into thepocket 288 prior to inserting the MOSFET 260 into the pocket 288. Thesolder can optionally be in the form of a metal foil. The retainingmember 264 can be a suitable electrically insulating plastic materialthat can be overmolded onto the MOSFET's 260 and heat sinks 262.

The plastic of the retaining member 264 can cohesively bond to theMOSFET's 260 and the heat sinks 262 to thereby fixedly couple theMOSFET's and heat sinks 262 to one another. Configuration in this mannereliminates relative motion between the MOSFET's 260 and between each ofthe MOSFET's 260 and its associated heat sink 262, as well as creates afluid-tight seal that inhibits fluid migration from the interior of thetransistor assembly 250 in a radially outward direction. The retainingmember 264 can carry a seal that can form a seal between the retainingmember 264 and the housing assembly 12.

If desired, the solder can be a relatively low temperature solder thathas a melting point that is below a predetermined target temperature.The target temperature can be a temperature that is below a maximumoperating temperature of the transistor assembly 250. For example, thetarget temperature can be the expected temperature of the transistorassembly 250 when the electric motor 14 (FIG. 1) was powered atapproximately 30%, 50%, or 80% of maximum power for a predetermined timeinterval, such as three hours. In such situation, the solder between thesurface-mount power terminal and the heat sink 262 would be expected tomelt from time to time during the operation of the electric drive module10 (FIG. 1). The melted solder would remain conductive and the retainingmember 264 would both inhibit relative movement between the MOSFET's 260and the heat sinks 262 but also inhibit migration of the liquid solderout of the pocket 288 and away from the interface between thesurface-mount power terminal and the bottom surface 288 a of the pocket288. As such, the melting of the solder would not impair operation ofthe electric motor 14 (FIG. 1). Furthermore, the solder would eventuallycool and re-bond the surface-mount power terminal to the bottom surface288 a of the pocket 288. It will be appreciated that different alloyscould be employed to tune the melt point of the solder to a desiredtemperature or temperature range.

With reference to FIG. 15, an annular end plate 290 can be fixedly andsealingly coupled to the retaining member 264. The end plate 290 caninclude a plurality of phase lead bosses 292, which can accept phaseleads 294 (FIG. 3) of the field windings 36 (FIG. 3) therethrough, aswell as an oil inlet port 296.

In FIGS. 3 and 4, the circuit board assembly 252 can comprise aplurality of printed circuit boards that can be stacked against oneanother and electrically coupled to the pin terminals of the MOSFET's260 as well as to the phase leads 294 of the field windings 36 of thestator 32. The quantity of printed circuit boards is dependent upon thethickness of the electrical traces or conductors on each of the printedcircuit boards and the amount of current that is to pass through betweeneach MOSFET 260 and an associated one of the field windings 36.

With reference to FIG. 16, the controller 206 is configured to sense arotational position of the rotor 34 relative to the stator 32 (FIG. 1)and responsively control the flow of electric power from the inverter204 (FIG. 3) to the field windings 36 (FIG. 3) to rotate the magneticfield that is produced by the field windings 36 (FIG. 3). The controller206 can include a second circuit board assembly that can comprise aplurality of stacked printed circuit boards. The second circuit boardassembly can have conventional hardware and control programming foroperating the electric motor 14 (FIG. 1) and a TMR sensor 300 that isconfigured to sense a rotational position of a magnetic field of amagnet 302 that is fixedly coupled to the rotor 34. The TMR sensor 300and the magnet 302 can optionally be used in place of a conventionalencoder or resolver. Significantly, the controller 206 uses directvoltage traces on the various printed circuit boards and/or the pins ofthe MOSFETS instead of resistors to determine current flow.

In FIG. 17, the housing assembly 12 is shown to have a pump mount 310, aheat exchanger mount 312 and a filter mount 314. The pump 24 can bemounted to the pump mount 310 and can circulate an appropriate fluidabout the electric drive module 10 to both lubricate and/or cool variouscomponents. In the example provided the fluid is a suitable dielectricfluid, such as automatic transmission fluid. The heat exchanger 26 canbe mounted to the heat exchanger mount 312 and can be configured toreceive a pressurized cooling fluid, such as a water-glycol mixture,from an external source and to facilitate the transfer of heat from thedielectric fluid circulated in the electric drive module 10 to thepressurized cooling fluid. The filter 28 can be any suitable filter,such as a spin-on oil filter, can be mounted to the filter mount 314,and can filter the dielectric fluid that is circulated within theelectric drive module.

With reference to FIGS. 18 through 20, an intake filter or screen 400can be disposed in a portion of the housing assembly 12 that houses thedifferential input gear 70. The intake filter 400 can receive dielectricfluid that can be returned to the low-pressure side of the pump 24. Awindage dam 402 can be integrated into a cover 404 and a main housingportion 406 of the housing assembly 12 to shield the dielectric fluidthat is being returned to the intake filter 400 from the differentialinput gear 70. More specifically, the windage dam 402 can causedielectric fluid to accumulate in the vicinity of the intake filter 400and segregate the accumulated fluid from the (rotating) differentialinput gear 70. It will be appreciated that without the windage dam 402,the rotating differential input gear 70 would tend to pull dielectricfluid away from the intake filter 400, which could prevent sufficientdielectric fluid from being returned to the low pressure (intake) sideof the pump 24. It will also be appreciated that segregating thedielectric fluid from the rotating differential input gear 70 can reducedrag losses that would otherwise be incurred from the rotation of thedifferential input gear 70 through the dielectric fluid. The cover 404can also include a tubular feed pipe 410.

With reference to FIGS. 21 and 22, a deflector 420 can be mounted to theplanet carrier PC and can shield the planetary reduction 42 fromdielectric fluid that is slung from other rotating components and/orcause dielectric fluid to drain from the planetary reduction 42 in adesired manner.

In FIGS. 23 and 24, dielectric fluid is received into the intake filter400 and transmitting to the low pressure (inlet) side of the pump 24.High pressure dielectric fluid exits the pump 24 and travels through aninternal gallery 430 in the housing assembly 12 to an inlet passage ofthe heat exchanger mount 312, through the heat exchanger 26, into anoutlet passage of the heat exchanger mount 312, into an inlet passage ofthe filter base 314, through the filter 28, into an outlet passage inthe filter mount 314 and to another internal gallery 432 in the housingassembly 12.

In FIGS. 25 and 26, dielectric fluid exiting the internal gallery 432can travel through a transfer tube 434 through the oil inlet port 296 inthe end plate 290 and can enter an annular cavity 440 that is locatedradially between a tubular central projection 442 on the end plate 290and the field windings 36. The central projection 442 can carry a sealthat can be sealingly engaged to the central projection 442 and to thefield windings 36. An annular gap 448 is formed between an axial end ofthe field windings 36 and an annular portion of the end plate 290. Asnoted previously, the end plate 290 is fixedly and sealingly coupled tothe retaining member 264 of the transistor assembly 250.

In FIG. 27, the dielectric fluid is shown to flow through the annulargap 448, through the fins 282 in the heat sinks 262 and into passages450 formed axially through the stator 32. While the fins 282 have beendepicted herein as perpendicular projections, it will be appreciatedthat the fins 282 could be shaped differently (for example, as diamondshaped projections) to cause the flow of dielectric fluid passingthrough the fins 282 to move in both tangential and axial directions.Flow in this manner may be beneficial for rejecting more heat from theheat sinks 262 into the dielectric fluid and/or to produce a desiredflow restriction that can aid in the pressure balancing of the coolingflow to the rotor. Accordingly, it will be appreciated that dielectricfluid is introduced to the inverter 204, passes through fins 282 on heatsinks 262 that are electrically conductively coupled to power terminalsof the MOSFET's 260 to thereby cool the inverter 204, and thereafterenters the passages 450 in the stator 32 to cool the stator 32 as isshown in FIG. 28.

In FIGS. 29 and 30, dielectric fluid exiting the stator 32 is collectedin an annular cavity 460 on an opposite end of the stator 32 thatpermits the velocity of the dielectric fluid to slow. A portion of thedielectric fluid is returned to a sump (not shown) in the housingassembly 12, while other portions of the flow are directed to lubricatevarious other components. For example, the annular cavity 460 can be influid communication with a worm track 464.

With reference to FIGS. 31 through 33, the worm track 464 can have anoutlet that can discharge the dielectric fluid into a bearing 470, whichcan support the differential case 472 for rotation relative to thehousing assembly 12, and/or onto the stub shaft 90, where the dielectricfluid can migrate to the opposite axial ends of the stub shaft 90 tolubricate the differential gearing and the bearing 94. Thereafter, thedielectric fluid can drain to the sump where it can flow into the intakefilter 400 (FIG. 23).

In FIGS. 34 and 35, the annular cavity 460 can be in fluid communicationwith a passage 480 that provides a flow of the dielectric fluid to abearing 482 that supports the rotor shaft 38 relative to the housingassembly 12. Dielectric fluid that is discharged from the bearing 482can seep between the housing assembly 12 and the rotor shaft 38 and candrain to the sump in the housing assembly 12.

With reference to FIGS. 26, 27 and 36, a portion of the dielectric fluidin the annular cavity 440 can be discharged into a bypass tube 500. Theamount of fluid that is discharged into the bypass tube 500 is based onpressure balancing between the flow that is directed through the bypasstube 500 and the portion of the flow that travels through the inverter204 and the stator 32.

FIG. 37 depicts the dielectric fluid as it is discharged from theannular cavity 440 and transferred via the bypass tube 500 to the feedpipe 410 in the cover 404.

FIG. 38 depicts the bypass flow exiting the bypass tube 500, travelingthrough the feed pipe 410 in the cover 404 and being fed into a heatexchanger 506 that is mounted within the rotor shaft 38. The heatexchanger 506 receives the flow (inflow) of dielectric fluid along itsrotational axis, and then turns the flow at the opposite end of therotor 34 so that the flow of dielectric fluid flows concentrically aboutthe inflow toward the end of the rotor 34 that received the inflow ofthe dielectric fluid.

In FIGS. 39 and 40, the outflow of the dielectric fluid that exits theheat exchanger 506 in the rotor shaft 38 can be at least partly employedto lubricate the various components (i.e., bearings, shafts, gear teeth)of the planetary reduction 42, as well as the bearings 60 that supportthe shaft 44 of the transmission. Note that the feed pipe 410 in thecover 404 is received through a bore in the shaft 44. In the exampleprovided, the feed pipe 410 is a discrete component that is assembled tothe cover 404.

FIGS. 41 through 44 show various flows of dielectric fluid being used tolubricate various other components within the electric drive module.

With reference to FIGS. 45 through 72, another inverter constructed inaccordance with the teachings of the present disclosure is generallyindicated by reference numeral 204 a. Unless expressly described herein,the inverter 204 a can be generally similar to the inverter 204 (FIG. 3)described in detail above.

In FIG. 46, the transistor assembly 250 a has a retaining member 264 athat is formed as a discrete component and thereafter various othercomponents, including the surface mount MOSFET's 260, can be assembledto the retaining member 264 a. The retaining member 264 a defines aplurality of phase lead bosses 292 a, a plurality of current sensorlamination mounts 600 and a plurality of sensor mounts 602. Each of thephase lead bosses 292 a can be disposed axially through the retainingmember 264 a and can be disposed within an associated one of the currentsensor lamination mounts 600. Each of the phase lead bosses 292 a issized to receive portion of a corresponding phase lead (not shown) thatsupplies electric power to the electric motor. Each of the currentsensor lamination mounts 600 is a generally oval-shaped structure thatprojects axially from the bottom surface 290 a of the retaining member264 a. Each of the sensor mounts 602 is disposed proximate an associatedone of the current sensor lamination mounts 600 and defines a hollow,oval-shaped guide tube 604 that projects axially away from the bottomsurface 290 a of the retaining member 264 a. In this example, theretaining member 264 a defines a plurality of insulating shields 608that are spaced about the circumference of the retaining member 264 aand which extend axially from the bottom surface 290 a of the retainingmember 264 a. With additional reference to FIG. 47, each of theinsulating shields 608 is disposed about (e.g., concentrically about) acorresponding aperture 610 that is sized to receive a correspondingterminal from one of the MOSFET's 260. The insulating shields 608 helpto electrically insulate the terminals of the MOSFET's 260 from oneanother.

FIG. 47 shows a portion of the transistor assembly 250 a and depicts thepresence of an annular seal ring groove 612 about the perimeter of theretaining member 264 a. The seal ring groove 612 is configured toreceive an appropriate elastomeric seal (e.g., an O-ring) therein thatsealingly engages the retaining member 264 a and the housing assembly 12(FIG. 1).

With reference to FIGS. 48 and 49, a plurality of current sensorlaminations 620 are stacked onto each of the current sensor laminationmounts 600. The current sensor laminations 620 are formed of steel andare generally C-shaped so as to define a pair of end faces 622 that aredisposed on opposite sides of an associated guide tube 604. The currentsensor laminations 620 can be configured with locating features thatnest into or with locating features on adjacent ones of the currentsensor laminations 620 to help secure the current sensor laminations 620to one another. A generally C-shaped insulating member 624 can bedisposed on each stack of current sensor laminations 620 on an axialside of the stack that is opposite the bottom surface 290 a.

In FIG. 50, a Hall sensor 630 is disposed in an associated one of thesensor mounts 602. A proximal end of the Hall sensor 630 is mounted tothe circuit board so that the sensor portion 630 a of the Hall sensor630 is disposed parallel to end faces 622 of the current sensorlaminations 620 at a desired location along a sensing axis relative tothe stack of current sensor laminations 620. Because the sensor portion630 a of the Hall sensor 630 is disposed at some distance from theproximal end of the Hall sensor 630, it will be appreciated that itwould be relatively easy to bend the terminals 630 b of the Hall sensor630, which would affect the positing of the sensor portion 630 a of theHall sensor 630. The guide tube 604, however, is sized and locatedrelative to an associated one of the current sensor lamination mounts600 to receive the sensor portion 630 a of the Hall sensor 630 as thecircuit board is mounted to the retaining member 264 a and the MOSFET's260 and guide the sensor portion 630 a into a desired location betweenthe end faces 622.

With reference to FIGS. 51 and 52, each of the phase leads 294 a caninclude a conductor plate 640 and a receiver 642. The conductor plate640 can be formed of a suitable electrically-conductive material, suchas copper. Each conductor plate 640 can have a body 644 and a pluralityof protrusions 646 that extend radially outwardly from the body 644. Thebody 644 can overlie an associated one of the stacks of current sensorlaminations 620 and can define a receiver aperture 648 that can bedisposed in-line with a corresponding one of the phase lead bosses 292a. It will be appreciated that the insulating member 624 can inhibit thetransmission of electricity between the conductor plate 640 and thecurrent sensor laminations 620. Each of the protrusions 646 can definean aperture that is sized to receive a device terminal 270 of anassociated one of the MOSFET's 260.

The receiver 642 is formed of a plurality of individually bident-shapedmembers 650 that are linearly arranged (i.e., stacked back-to-front) andpermanently affixed to the conductor plate 640. Each bident-shapedmember 650 can be formed of an appropriate electrically conductivematerial, such as copper, and can have body 652 and a base 654. The body652 can define a pair of tines and a generally U-shaped opening. Each ofthe tines can have a protrusion or barb that is fixedly coupled to adistal end of the tine and which extends inwardly therefrom so as tonarrow the portion of the generally U-shaped opening that is oppositethe base 654. The base 654 is received into the receiver aperture 648 inan associated one of the conductor plates 640. In the example shown, thereceiver apertures 648 are formed along a straight line and as such, thebident-shaped members 650 that form the receiver 642 are arranged alongthe straight line. It will be appreciated, however, that one or more ofthe receiver apertures 648 could be arranged along a line that is shapeddifferently (e.g., an arcuate line) and that the associated set ofbident-shaped members 650 are similarly arranged along a differentlyshaped (i.e., non-straight) line.

It will be appreciated that each phase of electric power supplied to theinverter 204 a can be electrically coupled to a blade terminal (notshown) that is received into the generally U-shaped openings in thebident-shaped members 650 and electrically coupled to the receiver 642.The individual bident-shaped members 650 permit flexing of the tinesrelative to one another and ensure that the blade terminal electricallycontacts multiple ones of the tines (preferably all or substantially allof the tines) to transmit an associated phase of electric power throughthe receiver 642 and into the conductor plate 640, which transmits theassociated phase of electric power to a set of the MOSFET's 260.

In FIGS. 53 and 54, a first insulator 660 is abutted against the phaseleads 294 a on a side of the phase leads that is opposite the generallyC-shaped insulating members 624. The first insulator 660 can define afirst bus bar recess 662 and a plurality of first insulating collars664. The first bus bar recess 662 is disposed on an axial side of thefirst insulator 660 that is opposite the side that abuts the phase leads294 a. Each of the first insulating collars 664 is disposed about adevice terminal 270 of a respective one of the MOSFET's 260. Each firstinsulating collars 664 can having a first end, which can be receivedinto a mating recess that is formed in the retaining member 264 a. Itwill be appreciated that the first insulating collars 664 are disposedabout the device terminals 270 of the MOSFET's 260 that need beelectrically separated from a first bus bar 670 that is received intothe first bus bar recess 662. Holes are formed through the firstinsulator 660 to receive therethrough any electric terminals (e.g., thedevice terminals 270 of the MOSFET's 260) that need extend through thefirst insulator 660. Each of the first insulating collars 664 can bedisposed concentrically about a respective one of the holes.

In the example shown the retaining member 264 a defines a flange 672,which is disposed circumferentially about the device terminals 270 ofthe MOSFET's 260.

With reference to FIGS. 53, 55 and 56, the first bus bar 670 is abuttedto the first insulator 660 and received into the first bus bar recess662. The first bus bar 670 has an annular bar body 676, a plurality ofprotrusions 678 that extend radially outwardly from the annular bar body676, and a power input portion 680. Each of the protrusions 678 is sizedto be received between the first insulating collars 664 of the firstinsulator 660 and to be electrically coupled to a respective one of thedevice terminals 270 of the MOSFET's 260. Holes are formed through theprotrusions and the power input portion 680 to receive device terminals270 from the MOSFET's 260 and from the terminals 684 of a pair ofcapacitors 686, respectively. A first slotted aperture 690 is formed inthe power input portion 680 to receive a blade terminal 692 thatelectrically couples the first bus bar 670 to a source of electricalpower (not shown).

With reference to FIGS. 53 and 57, a second insulator 700 can be mountedto the first bus bar 670 on a side opposite the first insulator 660.Like the first insulator 660, the second insulator 700 can extend overthe power input portion 680, can have a plurality of holes for receiptof various device terminals 270 and terminals 684 therethrough and candefine a plurality of (second) insulating collars 706 that can bedisposed about the device terminals 270 of the MOSFET's 260 toelectrically separate those device terminals 270 of the MOSFET's 260that will not be electrically coupled a second bus bar 710. Each of thesecond insulating collars 706 can define a pair of hollow, tubularprojections that can project in opposite axial directions. The tubularprojections on the side of the second insulator 700 that face toward thefirst insulator 660 can be matingly received into recesses that aredefined by the first insulating collars 664.

With reference to FIGS. 53 and 58, the second bus bar 710 is abutted tothe second insulator 700. The second bus bar 710 has an annular bar body712, a plurality of protrusions 714 that extend radially outwardly fromthe annular bar body 712 and a power input portion 716. Each of theprotrusions 714 is sized to be received between the second insulatingcollars 706 of the second insulator 700 and to be electrically coupledto a respective one of the device terminals 270 of the MOSFET's 260.Holes are formed through the protrusions 714 and the power input portion716 to receive the device terminals 270 from the MOSFET's 260 and fromthe terminals 720 of the pair of capacitors 686, respectively. A secondslotted aperture 722 is formed in the power input portion 716 to receivea blade terminal 724 that electrically couples the second bus bar 710 toa source of electrical power (not shown)

With reference to FIGS. 53 and 59, a third insulator 730 is mounted tothe retaining member 264 a and abuts the second bus bar 710 on a sideopposite the second insulator 700. The third insulator 730 defines asecond bus bar recess 732 into which the second bus bar 710 is received.The third insulator 730 also defines a plurality of third insulatingcollars 734 and a plurality of holes. Each of the third insulatingcollars 734 can define a recess that can receive a tubular projectionfrom an associated one of the second insulating collars 706 of thesecond insulator 700. The holes can extend through the third insulator730 to receive there through various terminals, such as the deviceterminals 270 of the MOSFET's 260, so that those terminals can beelectrically coupled to the circuit board 740. The third insulator 730can define first and second flange members 742 and 744, respectively,that can extend axially from a central body of the third insulator 730in opposite axial directions. Each of the first and second flangemembers 742 and 744 is disposed about the perimeter of the central bodyof the third insulator 730. The flange 672 of the retaining member 264 acan be received within (and optionally can abut) the second flangemember 742 to form a labyrinth about a cavity that is defined by theretaining member 264 a and the third insulator 730.

In FIGS. 53 and 60, the circuit board 740 can be abutted to the thirdinsulator 730 on a side opposite the second bus bar 710 and can beelectrically coupled to the various terminals that extend through thethird insulator 730.

In FIGS. 61 through 63 a control board 750 is plugged into the circuitboard 740 and is fixedly coupled thereto via a plurality of threadedfasteners 752. The control board 750 is disposed about the transfer tube434 that is mounted to a bearing support 754 that holds a bearing 756that supports a rotor shaft 38 of the electric motor relative to thehousing of the electric motor. The transfer tube 434 is sealinglyengaged to the oil inlet port 296 that is unitarily and integrallyformed with the retaining member 264 a (FIG. 46). Coolant received bythe oil inlet port 296 in the retaining member is employed to routecooling liquid to the inverter 204 a and to the electric motor.

In FIGS. 64 through 67, a portion of the flow of the filtered coolantthat is discharged from the heat exchanger 26 is routed to thecapacitors 686 to cool the capacitors 686. Coolant discharged from thecapacitors 686 is routed to join the flow of cooling liquid enters thestator 32 to cool the electric motor.

The capacitors 686 are illustrated in FIG. 68 as being mounted to a tray780 that holds a seal member 782. Optional crush limiters 784 can bemounted to the tray 780 to limit the amount by which the seal member 782is compressed. FIG. 69 depicts the reverse side of the tray 780 and theterminals 684, 720 of the capacitors 686. The capacitors 686 can bepotted to the tray 780 with a suitable compound to form a seal betweenthe capacitors 686 and the tray 780.

FIG. 70 depicts a recess 790 in the housing that is configured toreceive the tray 780 (FIG. 68) and the capacitors 686 (FIG. 68). Agallery 792 that is integrally formed with the housing permits coolingfluid in the recess 790 to be discharged through a housing wall 796 tothe stator 32 (FIG. 64) of the electric motor.

FIG. 71 depicts the tray 780 being mounted to the housing via aplurality of threaded fasteners.

FIG. 72 depicts a fourth insulator 800 that is disposed between thecircuit board 740 and the bearing support 754. The fourth insulator 800can have a flange 810 about its perimeter that can be received into thefirst flange 742 on the third insulator 730 to form a labyrinth betweenthe third and fourth insulators 730 and 800.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. An electric drive unit comprising: a statorhaving a stator body and a plurality of sets of field windings, thestator body defining a plurality of cooling channels that extendlongitudinally through the stator body, each of the sets of fieldwindings being fixedly coupled to the stator body and beingcircumferentially spaced apart about a central longitudinal axis; arotor received in the stator and rotatable about the centrallongitudinal axis; and an inverter assembly that includes a plurality ofpower semiconductors, a plurality of heat sinks and an end plate, eachof the power semiconductors being thermally coupled to a correspondingone of the heat sinks, each of the heat sinks having a plurality of finsthat extend into a flow channel that is coaxial with the plurality ofsets of field windings, the end plate being coupled to the powersemiconductors and having a projection and a coolant port, theprojection being sealingly coupled to the plurality of sets of fieldwindings and partly defining an annular cavity, the coolant port beingcoupled in fluid communication with the annular cavity, wherein the flowchannel is in fluid communication with and disposed in a flow pathbetween the annular cavity and the cooling channels in the stator body.2. The electric drive unit of claim 1, wherein the flow channel isdisposed radially between the plurality of sets of field windings andthe power semiconductors.
 3. The electric drive unit of claim 1, whereinthe flow channel is disposed radially outwardly of the plurality of setsof field windings.
 4. The electric drive unit of claim 1, wherein anannular gap is formed axially between the end plate and an axial end ofthe field windings, the annular gap fluidly coupling the annular cavityand the flow channel.
 5. The electric drive unit of claim 4, wherein aradially inward end of the annular gap intersects the annular cavity,and a radially outward end of the annular gap intersects the flowchannel.
 6. The electric drive unit of claim 1, wherein the tubularprojection carries a seal member that is sealingly mounted to thestator.
 7. The electric drive unit of claim 1, wherein the inverterassembly further comprises first and second bus bars, each of the firstand second bus bars having an annular bar body that is electricallycoupled to at least a portion of the power semiconductors.
 8. Theelectric drive unit of claim 7, wherein the inverter assembly furthercomprises a plurality of conductor plates, each of the conductor platesbeing electrically coupled to a corresponding set of the powersemiconductors and to a phase lead of a corresponding one of the sets offield windings.
 9. The electric drive unit of claim 8, wherein theinverter assembly further comprises a current sensor lamination mount, asensor mount, a plurality of generally C-shaped sensor laminations and aHall-effect sensor, the current sensor lamination mount being coupled tothe end plate, the sensor mount being a tubular structure that projectsfrom the current sensor lamination mount, the generally C-shaped currentsensor laminations being disposed on the current sensor lamination mountand having open ends that are disposed on opposite sides of the sensormount, the Hall-effect sensor being received in the sensor mount anddisposed between the opposite open ends of the generally C-shapedcurrent sensor laminations, wherein the generally C-shaped currentsensor laminations are received about a portion of one of the phaseleads.
 10. The electric drive unit of claim 8, wherein each of the phaseleads comprises a receiver that defines a slotted aperture.
 11. Theelectric drive unit of claim 10, wherein the receiver comprises aplurality of individually bident-shaped members.
 12. The electric driveunit of claim 1, further comprising a transmission having a transmissioninput member that is coupled to the rotor for rotation therewith. 13.The electric drive unit of claim 12, further comprising a differentialassembly having a differential input member, which is driven by atransmission output member of the transmission, and a pair ofdifferential output members.
 14. The electric drive unit of claim 13,wherein the differential input member is a differential case and whereinthe differential output member is fixedly coupled to the differentialcase.
 15. The electric drive unit of claim 1, wherein the inverterassembly further comprises a TMR sensor, wherein a magnet is coupled tothe rotor for rotation therewith, and wherein the TMR sensor senses arotational position of magnet.
 16. An electric drive unit comprising: amotor assembly having an electric motor and an inverter assembly, theelectric motor having a plurality of sets of field windings and defininga plurality of cooling channels, each of the sets of field windingsincluding a phase terminal, the inverter assembly having a retainer, aplurality of power semiconductors, a circuit board, first and second busbars, a plurality of conductor plates, and a plurality of heat sinks,the retainer including an annular end plate that is sealingly coupled tothe electric motor, each of the power semiconductors having a pluralityof device terminals that are received through the annular end plate,each of the power semiconductors being electrically coupled to the firstand second bus bars, each of the conductor plates being electricallycoupled to a corresponding set of the power semiconductors and acorresponding one of the phase terminals, the heat sinks beingmechanically and thermally coupled to the power semiconductors; whereinthe power semiconductors and the heat sinks are disposed concentric withthe plurality of sets of field windings; wherein the end plate defines acoolant tube; wherein the end plate and the electric motor cooperate toform an annular cavity that is in fluid communication with the coolanttube; wherein the heat sinks have fins that are disposed in a flowchannel, and wherein the flow channel is disposed in fluid communicationbetween the annular cavity and the cooling channels.
 17. The electricdrive unit of claim 16, wherein the flow channel is disposed radiallybetween the plurality of sets of field windings and the powersemiconductors.
 18. The electric drive unit of claim 16, wherein theflow channel is disposed radially outwardly of the plurality of sets offield windings.
 19. The electric drive unit of claim 16, wherein anannular gap is formed axially between the end plate and an axial end ofthe field windings, the annular gap fluidly coupling the annular cavityand the flow channel.
 20. The electric drive unit of claim 19, wherein aradially inward end of the annular gap intersects the annular cavity,and a radially outward end of the annular gap intersects the flowchannel.